The necessity of resorting to a manual operation for finally emptying the silo represents a serviture, a source of slow execution and high cost price.
Various devices are known for mechanically ensuring final evacuation of the remaining granulous material when evacuation by gravity has ended.
Fixed or mobile pneumatic devices are known which automatically guide the mass of the grain remaining on the floor towards the evacuation orifices.
However, these devices are complex to place in position and represent considerable investment; in fact, it is necessary to provide a high blowing power, whilst this installation is called upon to function only over a very limited period of time corresponding to the complete evacuation of the silo.
Conveying means such as described in U.S. Pat. No. 1,826,840 and especially endless conveyors disposed parallel to the front of the heap and advancing towards the heap of the bulk material so as laterally to evacuate the said material are not suitable since they are likely to get stuck or jammed in the heap if their advance towards the heap is too fast and they are likely to rotate idly if their advance towards the heap is too slow; so that said endless conveyors must remain under the control of the staff especially where the heap of bulk material is not of regular shape, so as constantly to adapt the advance of the said conveyor towards the heap as a function of the evacuation flow; the evacuation conveyor must be allowed to advance towards the heap only to maintain the appropriate position of the conveyor with respect to the base of the heap being evacuated.